1. Field of the Invention
The invention relates in general to overhead lighting systems for growing plants, and more particularly, to systems for delivering light to plants to stimulate plant growth, produce strong and healthy plants, and increase plant yields.
2. Description of the Prior Art
Various techniques and apparatuses have been developed over the years to increase growth rates and increase yields of plants in order to meet research demands and the worldwide need for increased food supplies. Because plant growth is limited mostly by light, moisture, and nutrients, the provision of these, in both natural and controlled environments, has been the focus of much of the development in this area.
Light is the primary energy source for photosynthesis which, in turn, is the process by which most of the plant growth occurs. Without the proper amount of light, plants are not as productive as they could be. In controlled environments provision of adequate light is a major challenge. Therefore, light delivering apparatuses of one kind or another have been widely used. Overhead lights have often been installed in a controlled and enclosed environment to deliver light to plants. But, if the enclosed environment is designed to take cost-saving advantage of natural light, overhead lights are somewhat counterproductive in that they produce shade on the upper leaves of at least some of the plants. Often the position of prior art overhead lights are vertically fixed so that smaller plants may not receive the amount of light they need. In addition, the makeup of the prior art lights often produce heat which, in combination with heat produced in a controlled environment by natural light, exceeds the heat tolerance of the very plants for which the benefit of light is being provided.
Accordingly, in view of the deficiencies of prior art lighting systems, what is needed is an apparatus that will allow adjustable vertical placement of lights correlated to plant heights and which creates minimal shade and minimal heat.
Prior art has addressed the problems of delivering light by vertically adjustable means for the theater stage, for medical apparatus delivering radiation or light, and for lighting needs in work areas of offices and factories. For plant growth, prior art discloses mounted reflective louvers with attitude adjustment to direct natural light and the widely used, vertically stationary, suspended lights. The apparatus for delivering light to stage borders disclosed in U.S. Pat. No. 1,055,020 to Camph is specific to lighting for theater stages and teaches the use of counterweights and pulleys to control the vertical placement of a light from the opposite side of the stage.
Another U.S. Pat. No. 4,358,817 to Bielemeier discloses a vertically adjustable lighting apparatus for a cosmetic or medical radiation emitting device. The Bielemeier invention concerns a relatively complicated system of drive shaft and winding drums mounted in a frame which move vertically with the lights and placement of suspension straps to decrease swing of the apparatus. Such patent also refers to a known device where the motor and spaced apart reels were mounted near the ceiling and worked to raise and lower the frame on which lights were mounted. However, in the prior art referenced by Bielemeier horizontal swing and oblique positioning were a problem which Bielemeier's teachings addressed via placement of suspension straps.
Yet another U.S. Pat. No. 3,409,262 to Soule provides an apparatus for raising and lowering lights in factories and larger buildings. The Soule apparatus consists of a pulley system connected to a motor which allows suspended light fixtures to be raised and lowered for maintenance and to address lighting needs in the workplace.
None of the prior art teachings referred to above show or suggest that the inventions disclosed are useful for stimulating the growth of plants. Furthermore, even the application of such prior art to delivering light to plants would not address many of the problems encountered by using overhead lighting to stimulate plant growth in a controlled environment. Although the Bielemeier patent teaches a system employed to minimize swing, the system is relatively complex and contemplates the mechanics as part of the light frame. This would require a larger frame and, hence, create more shade in natural light. Soule's teachings include a complex pulley system for vertical adjustment and does not adequately accommodate for horizontal swing. Moreover, neither the Bielemeier or Soule patent disclose structures that minimize the heat generated by the lights themselves.
It is therefore one object of the invention to provide a simple means for raising and lowering overhead lighting apparatus without creating additional bulk and shade.
It is another object of the invention to provide a means to greatly reduce horizontal swing of the lighting apparatus.
It is, finally, an object of the invention to reduce the heat produced by the plurality of lights in the apparatus.